1. Technical Field
The present invention relates to methods for fabricating semiconductor devices, and more particularly, to a method for fabricating a semiconductor device using a nickel salicide process.
2. Discussion of the Related Art
As integration density and operational speed of semiconductor devices increase, materials having low resistivity are more widely used in semiconductor devices to reduce signal delay. There has been an increased interest in a silicide material having very low resistivity for lowering sheet resistance and contact resistance of a gate pattern and a source/drain region of a transistor. A salicide process has been applied to form a silicide layer on a gate pattern and a source/drain region of a transistor.
The salicide process typically uses cobalt for a silicide material. However, as the gate width of a semiconductor device is reduced to 100 nm or less, the cobalt salicide process has several problems. As denoted by reference numeral A of FIG. 1A, cobalt silicide formed on a gate pattern is either shorted or cut. Also, as denoted by reference numeral B of FIG. 1B, a pit is formed in a boundary area between an active region and a field region. In addition, as the gate width of a semiconductor device is reduced to 100 nm or less, the cobalt salicide process leads to the lumping of cobalt silicide.
The foregoing problems result from a high-temperature thermal treatment for changing cobalt silicide from CoSi-type to CoSi2-type. Accordingly, there have been proposals to use a nickel salicide process in highly integrated semiconductor devices. This process requires no high-temperature thermal treatment. However, the nickel salicide process causes a silicide residue to form on a spacer and a field region and a field oxide layer formed on a silicon substrate.
Therefore, a need exists for fabricating a semiconductor device using a nickel salicide process that prevents a silicide residue from forming on a spacer and a field region.